000 FXUS63 KMKX 250926 AFDMKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 326 AM CST WED NOV 25 2009 .DISCUSSION...FORECAST FOCUS IS ON COMPLEX SYSTEM FOR TONIGHT INTO EARLY THANKSGIVING DAY. TODAY- WATER VAPOR/RUC COMBO SHOWS CENTER OF CIRCULATION IN NORTHERN ILLINOIS. CLOSED CIRCULATION EVOLVES INTO OPEN WAVE AND LIFTS NORTHEAST THIS MORNING. FOCUSED PRECIP ASSOCIATED WITH DECENT 700 OMEGA AND DEFORMATION ZONE EXPECTED TO BECOME LESS ORGANIZED WITH TIME. STILL NEED SOME PRETTY HEFTY POPS THIS MORNING EVEN THOUGH QPF BECOMES LESS ORGANIZED. A BRIEF SHORTWAVE RIDGE TAKES HOLD...BUT VERY BRIEF. NEXT UPPER LOW DROPS INTO SOUTHERN IOWA BY 00Z THURSDAY. 700 MILLIBAR LOW MOVES INTO EASTERN IOWA THIS AFTERNOON. APPRECIABLE FORCING NOTED IN THE SOUTHWEST HALF OF THE CWA AS A RESULT. HAVE CATEGORICAL POPS THIS AFTERNOON IN THE SW WITH LESSER POPS NE. TONIGHT- THE CLEAR CHALLENGE RESTS IN THIS PERIOD AND WHAT TO DO WITH PRECIP TYPE. THE COLD INFLUX THAT WAS EARLIER SLATED TO INVADE THE WESTERN CWA IS NOW DIVING FURTHER SOUTH WHILE AN 850 THERMAL RIDGE WRAPS INTO THE CWA FROM THE EAST. THE 12Z NAM HAD 850 TEMPS DOWN TO -4C AND NOW THE COLDEST IS -2C. LOOKING OVER THE BUFKIT SOUNDINGS THE POTENTIAL FOR FROZEN PRECIP HAS DIMINSIHED CONSIDERABLY. ALSO THE CROSSHAIRS SIGNATURE SHOWS DECENT OMEGA WITHIN THE SNOW GROWTH REGION HOWEVER THE BEST RH LIES BENEATH THE OVERLAY...AND THE POTENTIAL FOR CONVECTION IS ROOTED ABOVE THE SNOW GROWTH REGION. THE UPPER LOW TRACK IS FURTHER SOUTH ON THE GFS. STILL CONCERNED THOUGH... THE 700 MILLIBAR FORCING AND DEFORMATION ZONE REMAINS IMPRESSIVE. IF THE COLUMN WERE TO COOL QUICKER THAN WHAT MODELS SUGGEST...SNOW AMOUNTS WOULD OBVIOUSLY BE IN THE NEIGHBORHOOD OF WHAT WAS PREVIOUSLY THOUGHT. FOR NOW...WILL STEER TOWARDS WHAT THE BULK OF EVIDENCE IS SUGGESTING WITH RESPECT TO THE LOW LEVEL THERMAL PROFILE AND TREND SNOW AMOUNTS DOWN...GOING WITH A MIX IN THE WEST AFTER MIDNIGHT. THURSDAY- SURFACE/850 TROUGHS MOVE EAST OF THE STATE WITH SOME PRECIP LINGERING IN DEFORMATION ZONE. ECMWF SHOWING HIGHER QPF IN THE SOUTHEAST. SOUNDINGS FROM ECMWF/GFS AND NAM SHOW MILWAUKEE COULD STAY ALL RAIN TIL CONCLUSION OF EVENT. HOWEVER WILL BRING SOME TRANSITION TO A MIX FURTHER EAST. DRIER AIR STARTS TO WORK IN FOR THE AFTERNOON. FRIDAY- UPPER FLOW LARGELY ANTICYCLONIC WITH PRONOUNCED SURFACE/850 RIDGING. A WEAK RIPPLE SCOOTS THROUGH THE NW FLOW BUT PROBABLY NO MORE THAN MID/HIGH CLOUDS WITH THIS. 925 TEMPS MODERATE A BIT. SATURDAY- UPPER RIDGE BUILDS ACROSS THE AREA. 925 TEMPS SHOW EVEN NICER WARMING. COLUMN LOOKS LARGELY DRY. SUNDAY- TIMING DIFFERENCES BETWEEN ECMWF AND GFS IN SATURDAY NIGHT THROUGH SUNDAY NIGHT WITH RESPECT TO SURFACE LOW/TROUGH PASSAGE. AT THIS POINT IT LOOKS LIKE A LIGHT QPF EVENT THAT APPEARS TO BE LARGELY OF THE LIQUID VARIETY. && .AVIATION...IFR CEILINGS/VISIBILITIES AND AREAS OF LIFR CEILINGS EXPECTED AS SURFACE LOW MOVES ACROSS SOUTHEAST WISCONSIN THIS MORNING. SOME MVFR CIGS IN THE FAR SOUTHEAST AS OCCLUDED FRONT PUSHES IN SOME SLIGHTLY DRIER AIR. HOWEVER UPPER LOW/TROF WILL CONTINUE TO BRING A CHANCE OF SHOWERS. RATHER COMPLEX SITUATION WITH NEXT UPPER LOW DROPPING IN FROM THE NORTHWEST TONIGHT. IFR/LIFR CEILINGS AND MVFR/IFR VISIBILITIES WILL PREVAIL THROUGH THE NIGHT...WITH POCKETS OF MVFR CONDITIONS. WHILE UPPER LEVELS COOL...BOUNDARY LAYER WILL REMAIN RATHER WARM...SO CHANGEOVER TO A RAIN/SNOW MIX WILL OCCUR SLOWLY LATER TONIGHT. && .MARINE... WINDS AND WAVES WILL REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA WITH THE PASSING LOW PRESSURE SYSTEM ACROSS CENTRAL LAKE MICHIGAN THIS MORNING. BRISK NORTHWEST WINDS AND HIGHER WAVES ARE POSSIBLE THURSDAY AND THURSDAY NIGHT...AS THE SURFACE PRESSURE GRADIENT TIGHTENS AND COLD AIR ADVECTION BEGINS. HOWEVER THIS WILL BE LIMITED INITIALLY AS SECOND UPPER LOW DROPS IN FROM THE NORTHWEST...RESULTING IN LINGERING TROUGH OVER LAKE MICHIGAN AREA. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ SHORT/LONG TERM...COLLAR AVIATION/MARINE...HENTZ